In general, traditionally, sockets have been broadly classified into mass-produced type sockets and tester type sockets.
The mass-produced type socket is first soldered onto a substrate and then mounted with an electronic component, such that pads or the like of the substrate can be electrically connected with an external connection terminal (such as leads or solder balls) without directly soldering the external connection terminal of the electronic component to the pads of the substrate. Therefore, the mass-produced type socket has been used, for example, to mount electronic components or the like which are highly likely to be replaced.
Moreover, the tester type socket allows pads of test substrate to be electrically connected with an external connection terminal of the electronic component to be evaluated without directly soldering the external connection terminal to the pads of the test substrate when the electronic component itself is evaluated. Thus, the tester type socket has been essential for, for example, the inspection of the electronic component.
Various ideas have been made in connection with the above-mentioned sockets so that, for example, the electronic component can be easily replaced or the external connection terminal of the electronic component may not be damaged.
For example, in Japanese Patent Publication Laid-open No. H07-30019, there has been disclosed a technique of an IC socket in which a mechanism of confirming the loading of an IC is provided in an IC positioning table.
On the other hand, it has been increasingly essential to transmit a large volume of data at high speed along with the increasing volume in the data transmission. Electric wiring lines have various problems such as limits of throughput due to the length of the wiring line, an increase in power consumption, and an increase in noise such as radiation-field noise. An optical fiber transmission system has been researched and developed as effective means to solve the above problems, and is in practical use. For example, as far as communication among base stations is concerned, an increase in volume by means of optical communication has been achieved, and efforts have been made in connection with fiber to the office (FTTO) and fiber to the home (FTTH) in which optical fiber networks are provided to companies and households. Further, this system has wide range of uses, for example, in data transmission among boards of devices which transmit large volumes of data.
In the optical fiber transmission system, an optical module is used which converts an optical signal into an electric signal and vice versa. This optical module is different from a conventional electronic module which only handles electric signals, and comprises an external connection terminal which inputs and/or outputs electric signals as well as external optical signal connection means which inputs and/or outputs optical signals.